W3C home > Mailing lists > Public > public-media-capture@w3.org > June 2012

Re: Barcode Scanning scenario for media capture requirements

From: Rob Manson <roBman@mob-labs.com>
Date: Mon, 4 Jun 2012 09:56:54 +1000
To: public-media-capture@w3.org
Message-ID: <20120604095654.35795be9@robslapu2>
I think having the UA do recognition for things with standardised libs
(e.g. barcodes and qrcodes) is interesting and a good opportunity for
optimisation.  

As long as it's not solely limited to a UA centric model.  Recognition
of other things like faces, natural feature bundles (images) and even 3D
objects/scenes are all really fluid domains with constantly changing
and improving libraries.

I also wonder, if we have these 2 options (permissions for the
script/author and permissions for the UA) will this create a more
confusing permissions UX for the end user?

roBman


On Sun, 03 Jun 2012 11:47:08 -0700
Charles Pritchard <chuck@jumis.com> wrote:

> On 6/1/2012 3:14 PM, SULLIVAN, BRYAN L wrote:
> > I have some additional requirements from the Barcode Scanning use
> > case that has been discussed recently on the DAP and Sysapps lists.
> >
> > (suggested new section in
> > http://dvcs.w3.org/hg/dap/raw-file/tip/media-stream-capture/scenarios.html)
> >
> > 2.7 Barcode scanning
> > Users discover and access barcodes in many different contexts, e.g.
> > product packages, print media, posters, and billboards. Because
> > code interpretation in all these contexts depends upon capturing of
> > a usable image, the camera access API needs to enable the Webapp or
> > user to select options that will enhance the quality of the image.
> 
> I'd like to see detection of barcodes discussed as a Pre-processing 
> (section 5.5) scenario: "Pre-processing scenarios will require the
> UAs to provide an implementation".
> 
> The pseudo-code following example fits well with pre-processing while 
> avoiding the requirement of a camera controller API.
> 
> Sample events:
> {type: face, confidence: .6 }
> {type: barcode, confidence: .9 }
> {type: gesture, confidence, .5 }
> 
> Work-flow:
> 
> navigator.getUserMedia({video: true, recognition: true}, doVideo)
> doVideo().onrecognition(e) {
>    if(e.type == 'barcode') {
>      copyVideoFrame(e.mediaStream);
>      navigator.recognize(e, {autofocus: true, timeout: 2000, network: 
> false});
>    }
> }
> 
> Technical requirements:
> 
> 1. Power efficiency for mobile devices:
> By having the UA do basic recognition, we save a lot of cycles in the 
> scripting environment. (see also 5.6.2; performance)
> The author can save additional cycles by turning recognition off when 
> it's not needed.
> 
> 2. Control over side effects:
> Instead of the UA granting the author permission to do things like
> zoom and turn on a light,  the author grants those permissions to the
> UA.
> 
> 2a. autofocus would cover all available means the device has to
> better recognize the event type (light, zoom, focus, etc);
> 2b. timeout limits how long the UA has control of the device and/or
> the time it has to complete enhanced recognition.
> 2c. network limits the implementation from sending data over the
> network to recognition servers. (see also 5.1.1; privacy).
> 
> 
> Draft scenario:
> 
> Point out a barcode.
> 
> Alice brings a print-out to a kiosk, the print-out contains 2d bar
> codes next to each product.
> She wants to learn more about a particular product and so she simply 
> points at the product.
> 
> Recognition identifies her, her gesture and the barcodes on the page; 
> scripting processes the barcode closest to her finger.
> 
> -Charles
> 
Received on Sunday, 3 June 2012 23:57:23 UTC

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